The recent advances in production of micro- and nano-electronic devices has resulted in the need for new stripping and cleaning compositions for both front end of the line (FEOL) and back end of the line (BEOL) stripping or cleaning compositions. The cleaning compositions typically employed heretofore have not been found to be entirely suitable for the new advanced materials employed in production of microelectronic or nanoelectronic platforms. Frequently the previous employed stripping or cleaning compositions are too aggressive and/or are not selective enough. Among the newly utilized materials employed to produce these newer microelectronic or nanoelectronic devices are materials such as low-k (<3) and high-k (>20) and porous dielectrics, copper metallizations, fluoropolymer antireflective coatings (ARCs), special hard masks such as those composed of Ti and TiN, strained wafers of Si/Ge or Ge, and metal capping layers such as those of CoWP and CoWB. These new materials present new and difficult challenges to the device manufacturer.
For example, cleaning of Cu/low-κ structures not only requires good cleaning capabilities, but also needs exceptional substrate compatibilities. Many process technologies that have been developed for the “traditional” or common semiconductor devices containing Al/SiO2 or Al (Cu)/SiO2 structures cannot be applied to Cu/low-κ and high-κ structures. Vice versa, many Cu/low-κ strippers are not suitable for Al metallizations, unless significant adjustments are made.
The manufacturing processes of Cu/low-κ and/or high-κ structures frequently generate unusually hardened photoresist layers, tough plasma etching and/or ashing residues. Even highly aggressive reagents, such as HF acid, hydroxylamine and strong alkaline solutions, often fail to provide required cleaning with acceptable substrate compatibility.
Aqueous fluorides or HF based solutions have been used extensively as traditional FEOL and BEOL etchants and cleaning agents. Frequently, these types of cleaners are developed as oxide etcher or ash residue removers. For example, diluted HF (dHF) solutions and buffered oxide etch (BOE, consists of HF/NH4F/H2O) are effective oxide (silicon oxide) remover and limited residue cleaners, but generally non-effective in stripping photoresist.
A number of organic solvent-based or semi-aqueous solutions containing fluorides or HF have also been used in many BEOL applications. However, most of these products are still weak in multi-purpose applications such as removing plasma hardened photoresist and ARCs. They are also sometimes too aggressive, non-selective enough, or cannot meet new, highly demanding substrate compatibilities and selectivity requirements for advanced FEOL and BEOL applications with new challenging types of materials such as low-k and high-k and porous dielectrics, copper metallizations, fluoropolymer antireflective coatings (ARCs), special hard metal gates such as those of Ti and TiN, strained wafers of Si/Ge or Ge, and metal capping layers such as those of CoWP and CoWB. Thus, new and improved stripping or cleaning compositions are needed for multi-purpose applications in connection with these new material being employed on newer microelectronic and nanoelectronic devices.